Ceramic material, powder, and layer system comprising the ceramic material

ABSTRACT

An improved ceramic material for heat insulation with selection of specific stabilizers and adapted proportions, includes zirconium oxide with 0.2 wt. % to 8.0 wt. % of the base stabilizers: yttrium oxide (Y2O3), hafnium oxide (HfO2), cerium oxide (CeO2), calcium oxide (CaO), and/or magnesium oxide (MgO), wherein at least yttrium oxide (Y2O3) is used, and optionally at least one of the additional stabilizers: 0.2 wt. % to 20 wt. % of erbium oxide (Er2O3) and/or ytterbium oxide (Yb2O3).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/EP2020/057029 filed 18 Mar. 2020, and claims the benefitthereof. The International Application claims the benefit of GermanApplication No. DE 10 2019 217 445.0 filed 12 Nov. 2019. All of theapplications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a ceramic material and to powder producedtherewith that can be used for ceramic layer systems.

BACKGROUND OF INVENTION

Ceramics in general have a high thermal stability and are thereforeoften used as ceramic coatings on high-temperature components, such asturbines, especially gas turbines.

The constant aim is to improve the heat insulation properties of theceramic material.

SUMMARY OF INVENTION

It is therefore an object of the invention to solve the problemidentified above.

The object is achieved by means of a ceramic, a ceramic powder, and asystem of layers as claimed.

Ceramic layers based on zirconium oxide with stabilizers are known;here, fully stabilized zirconium oxide is often used, owing to itsbetter thermal stability.

The objective of the concept, however, is to use partially stabilizedzirconium oxide having an improved stability, especially thermalstability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 4 show exemplary embodiments of the invention.

DETAILED DESCRIPTION OF INVENTION

The zirconium oxide is stabilized with 0.2 wt % to 8 wt %, moreparticularly with 0.2 wt % to 6.0 wt %, of base stabilizers: yttriumoxide, hafnium oxide, cerium oxide, calcium oxide and/or magnesium oxideand optionally with additional stabilizers— 0.2 wt % to 20 wt % oferbium oxide and/or ytterbium oxide.

Yttrium oxide is used in any case and at least one of the basestabilizers hafnium oxide, cerium oxide, calcium oxide and/or magnesiumoxide is used.

This ceramic composition may be prepared as a powder, and so furtheradditions, as in the use of abrasive layers, comprise cubic boronnitride or other abrasive particles.

In a layer system 1 ^(I) (FIG. 1) a ceramic layer 10 ^(I) is applied tometal, the substrate 4 present, in the case of nickel- or cobalt-basedsuperalloys used preferably, being a metallic adhesion layer 7 whichforms aluminum oxide (TGO; not shown), with the metallic adhesionpromoter layer constituting preferably an aluminide, platinum-aluminideor, as a basis, an NiCoCrAlY alloy, optionally with x=Ta, Re, Fe and/orSi.

The ceramic layer of the ceramic material in accordance with theinvention may be produced by means of EB-PVD, plasma spraying (APS,etc.), etc. and has a columnar structure or a segmented structure.

The layer 10 ^(I), 10″, 10′″, 10 ^(IV) (FIGS. 2-4) preferably has alayer thickness of 100 μm to 1000 μm.

As shown in FIG. 2, a ceramic layer 10 ^(II) as in FIG. 1 may also havea ceramic sublayer 13 ^(II), the layer thickness of which, however, isat least 20% thinner in configuration than that of the ceramic materialof the invention in the ceramic layer 10 ^(II).

The ceramic sublayer 13 ^(II) preferably comprises 8YSZ, i.e., zirconiumoxide stabilized with 3 mol % to 4 mol % of yttrium, and is thereforedistinctly different from the material of the ceramic layer 10 ^(II).

FIGS. 3 and 4 show further examples of layer structures 1 ^(III), 1^(IV) of the invention.

According to FIG. 3, in comparison to FIG. 1, there is a segmentedceramic layer 10 ^(III) of a layer system 1 ^(III), which comprisesnumerous, relatively long and vertical cracks 15, 15 ^(I), starting fromthe surface 18 of the outermost ceramic layer 10 ^(III), and extendingvery largely over the entire ceramic layer thickness, here in particularup to the metallic adhesion layer 7 or the TGO thereof (not shown).

A layer system 1 ^(IV) may also comprise a ceramic attachment layer 13^(IV) (FIG. 4) for the outermost TBC 10 ^(IV), in which case theattachment layer 13 ^(IV) may be configured as described in FIG. 2.

The outermost ceramic layer 10 ^(IV) is more particularly configuredlike the outermost layer 10 ^(III) in FIG. 3.

In the ceramic attachment layer 13 ^(IV), however, cracks 14 extend,preferably likewise vertical, which extend through both ceramic layers10 ^(IV), 13 ^(IV).

The relatively long cracks have been formed by specific processparameters or production methods, and do not represent cracks betweenmultiple grains.

Exemplary Embodiments

ZrO₂+Y₂O₃+CeO₂ZrO₂+Y₂O₃+MgOZrO₂+Y₂O₃+HfO₂ZrO₂+Y₂O₃+CaOZrO₂+Y₂O₃+CeO₂+MgOZrO₂+Y₂O₃+MgO+HfO₂ZrO₂+Y₂O₃+HfO₂+CaOZrO₂+Y₂O₃+CeO₂+HfO₂ZrO₂+Y₂O₃+MgO+CaOZrO₂+Y₂O₃+CeO₂+CaOZrO₂+Y₂O₃+CaO+CeO₂+HfO₂ZrO₂+Y₂O₃+HfO₂+MgO+CaOZrO₂+Y₂O₃+CeO₂+MgO+CaOZrO₂+Y₂O₃+CeO₂+MgO+HfO₂ZrO₂+Y₂O₃+HfO₂+CaO+CeO₂+MgOZrO₂+Y₂O₃+CeO₂+Yb₂O₃ZrO₂+Y₂O₃+MgO+Yb₂O₃ZrO₂+Y₂O₃+HfO₂+Yb₂O₃ (particularly preferred)ZrO₂+Y₂O₃+CaO+Yb₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+Yb₂O₃ZrO₂+Y₂O₃+MgO+HfO₂+Yb₂O₃ZrO₂+Y₂O₃+HfO₂+CaO+Yb₂O₃ZrO₂+Y₂O₃+CeO₂+HfO₂+Yb₂O₃ZrO₂+Y₂O₃+MgO+CaO+Yb₂O₃ZrO₂+Y₂O₃+CeO₂+CaO+Yb₂O₃ZrO₂+Y₂O₃+CaO+CeO₂+HfO₂+Yb₂O₃ZrO₂+Y₂O₃+HfO₂+MgO+CaO+Yb₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+CaO+Yb₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+HfO₂+Yb₂O₃ZrO₂+Y₂O₃+HfO₂+CaO+CeO₂+MgO+Yb₂O₃ZrO₂+Y₂O₃+CeO₂+Er₂O₃ZrO₂+Y₂O₃+MgO+Er₂O₃ZrO₂+Y₂O₃+HfO₂+Er₂O₃ZrO₂+Y₂O₃+CaO+Er₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+Er₂O₃ZrO₂+Y₂O₃+MgO+HfO₂+Er₂O₃ZrO₂+Y₂O₃+HfO₂+CaO+Er₂O₃ZrO₂+Y₂O₃+CeO₂+HfO₂+Er₂O₃ZrO₂+Y₂O₃+MgO+CaO+Er₂O₃ZrO₂+Y₂O₃+CeO₂+CaO+Er₂O₃ZrO₂+Y₂O₃+CaO+CeO₂+HfO₂+Er₂O₃ZrO₂+Y₂O₃+HfO₂+MgO+CaO+Er₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+CaO+Er₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+HfO₂+Er₂O₃ZrO₂+Y₂O₃+HfO₂+CaO+CeO₂+MgO+Er₂O₃ZrO₂+Y₂O₃+CeO₂+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+MgO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+HfO₂+Yb₂O₃+Er₂O₃ (particularly preferred)ZrO₂+Y₂O₃+CaO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+MgO+HfO₂+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+HfO₂+CaO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+CeO₂+HfO₂+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+MgO+CaO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+CeO₂+CaO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+CaO+CeO₂+HfO₂+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+HfO₂+MgO+CaO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+CaO+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+CeO₂+MgO+HfO₂+Yb₂O₃+Er₂O₃ZrO₂+Y₂O₃+HfO₂+CaO+CeO₂+MgO+Yb₂O₃+Er₂O₃

The ceramic material comprises preferably 2.5 wt % to 5.5 wt % ofyttrium oxide (Y₂O₃), more particularly 3.0 wt % to 5.0 wt % of yttriumoxide (Y₂O₃), especially 3.5 wt % to 4.0 wt %.

The ceramic material may also comprise preferably 1.5 wt % to 3.0 wt %of yttrium oxide (Y₂O₃), more particularly 2.0 wt % to 2.5 wt % ofyttrium oxide (Y₂O₃).

The ceramic material preferably comprises: hafnium oxide (HfO₂) at 0.2wt % to 4.0 wt %, more particularly 0.5 wt % to 4.0 wt % of hafniumoxide (HfO₂), especially 0.6 wt % to 4.0 wt % of hafnium oxide (HfO₂).

For better, i.e., lower, thermal conductivity, the ceramic materialpreferably comprises: hafnium oxide (HfO₂) at 0.2 wt % to 2.0 wt %, moreparticularly at 0.6 wt % to 2.0 wt % of hafnium oxide (HfO₂), especiallyat 0.8 wt % to 2.0 wt % of hafnium oxide (HfO₂).

For better thermal stability the ceramic material preferably comprises:hafnium oxide (HfO₂) at 2.0 wt % to 4.0 wt %, more particularly 2.4 wt %to 4.0 wt % of hafnium oxide (HfO₂), especially 4.0 wt % to 4.0 wt % ofhafnium oxide (HfO₂).

The ceramic material preferably comprises 5.5 wt % to 8.5 wt % ofytterbium oxide (Yb₂O₃), more particularly 6.0 wt % to 8.0 wt % ofYb₂O₃, especially 6.5 wt % to 7.5 wt % of Yb₂O₃.

The ceramic material comprises preferably 3.0 wt % to 4.5 wt % ofytterbium oxide (Yb₂O₃), more particularly 3.5 wt % to 4.0 wt % ofytterbium oxide (Yb₂O₃).

The ceramic material also preferably comprises 2.0 wt % to 4.0 wt % ofEr₂O₃, more particularly 2.5 wt % to 3.5 wt % of Er₂O₃.

With further preference the ceramic material comprises (6.0-x) wt % ofY₂O₃+(2-4) x wt % of Yb₂O₃/Er₂O₃, i.e., at 4.0 wt % of Y₂O₃, xcorresponds to 2 and the fraction of Yb₂O₃/Er₂O₃ is (2-4)*2, i.e.,between 4 wt % and 8 wt %.

1. A ceramic material based on zirconium oxide (ZrO₂) with 0.2 wt % to8.0 wt % of base stabilizers:, more particularly with 0.2 wt % to 6.0 wt% of base stabilizers: yttrium oxide (Y₂O₃), hafnium oxide (HfO₂),cerium oxide (CeO₂), calcium oxide (CaO) and/or magnesium oxide (MgO),wherein at least yttrium oxide (Y₂O₃) is used, and optionally at leastone of the additional stabilizers: 0.2 wt % to 20 wt % of erbium oxide(Er₂O₃) and/or ytterbium oxide (Yb₂O₃).
 2. The ceramic material asclaimed in claim 1, comprising: at least 0.5 wt % and not more than 6.0wt % of yttrium oxide (Y₂O₃).
 3. The ceramic material as claimed inclaim 1, comprising: 2.5 wt % to 5.5 wt % of yttrium oxide (Y₂O₃), moreparticularly 3.0 wt % to 5.0 wt % of yttrium oxide (Y₂O₃), especially3.5 wt % to 4.0 wt % of yttrium oxide (Y₂O₃).
 4. The ceramic material asclaimed in claim 1, comprising: 1.5 wt % to 3.0 wt % of yttrium oxide(Y₂O₃), more particularly 2.0 wt % to 2.5 wt % of yttrium oxide (Y₂O₃).5. The ceramic material as claimed in claim 1, which comprises: at leastyttrium oxide (Y₂O₃) and hafnium oxide (HfO₂) as base stabilizers, andmore particularly comprises only yttrium oxide (Y₂O₃) and hafnium oxide(HfO₂) as base stabilizers.
 6. The ceramic material as claimed in claim1, wherein the hafnium oxide (HfO₂) content is 0.2 wt % to 4.0 wt %,more particularly 0.6 wt % to 4.0 wt % of hafnium oxide (HfO₂),especially 0.8 wt % to 4.0 wt % of hafnium oxide (HfO₂).
 7. The ceramicmaterial as claimed in claim 1, which comprises: at least one of theadditional stabilizers erbium oxide (Er₂O₃) and/or ytterbium oxide(Yb₂O₃).
 8. The ceramic material as claimed in claim 1, comprising, moreparticularly consisting of, ZrO₂—HfO₂—Y₂O₃—Yb₂O₃.
 9. (canceled)
 10. Theceramic material as claimed in claim 1, comprising: 5.5 wt % to 8.5 wt %of ytterbium oxide (Yb₂O₃), more particularly 6.0 wt % to 8.0 wt % ofytterbium oxide (Yb₂O₃), especially 6.5 wt % to 7.5 wt % of ytterbiumoxide (Yb₂O₃).
 11. The ceramic material as claimed in claim 1,comprising: 3.0 wt % to 4.5 wt % of ytterbium oxide (Yb₂O₃), moreparticularly 3.5 wt % to 4.0 wt % of ytterbium oxide (Yb₂O₃). 12.(canceled)
 13. (canceled)
 14. The ceramic material as claimed in claim1, wherein the hafnium oxide (HfO₂) content is 0.2 wt % to 2.0 wt %,more particularly 0.6 wt % to 2.0 wt % of hafnium oxide (HfO₂),especially 0.8 wt % to 2.0 wt % of hafnium oxide (HfO₂).
 15. The ceramicmaterial as claimed in claim 1, wherein the hafnium oxide (HfO₂) contentis 2.0 wt % to 4.0 wt %, more particularly 2.4 wt % to 4.0 wt % ofhafnium oxide (HfO₂), especially 3.0 wt % to 4.0 wt % of hafnium oxide(HfO₂).
 16. A ceramic powder comprising, more particularly consistingof, a composition of a material as claimed in claim
 1. 17. A system oflayers at least comprising: a metallic substrate, optionally a metallicadhesion promoter layer, and an at least one ceramic layer (10 ^(I), 10^(II), 10 ^(III), 10 ^(IV)) based on the ceramic material as claimed inclaim
 1. 18. The layer system as claimed in claim 17, comprising: ametallic adhesion promoter layer between the ceramic layer (13 ^(II), 13^(IV); 10 ^(I), 10 ^(III)) and the metallic substrate, more particularlydirectly on the substrate, wherein the adhesion promoter layer comprisesan alloy of the type NiCoCrAlY—X, X being optionally=Ta, Re and/or Si,more particularly NiCoCrAlY or NiCoCrAlY—Ta.
 19. The layer system asclaimed in claim 17, wherein a ceramic sublayer (13 ^(II), 13 ^(IV)) ispresent below the ceramic layer (10 ^(II), 10 ^(IV)), which moreparticularly is at least 20% thinner in configuration and comprisesyttrium-stabilized zirconium oxide (YSZ), more particularly 8YSZ, i.e.,zirconium oxide stabilized with 3 mol % to 4 mol % of yttrium.
 20. Thelayer system as claimed in claim 17, which comprises a segmentation,more particularly by means of relatively long vertical cracks (14; 15,15 ^(I)), in the one or more ceramic layers (10 ^(III), 10 ^(IV); 13^(IV)), more particularly also in the ceramic sublayer (13 ^(IV)). 21.The layer system as claimed in claim 20, in which the segmentation ispresent by means of vertical cracks (15, 15 ^(I)) only in the outermostceramic layer (10 ^(III), 10 ^(IV)).
 22. The layer system as claimed inclaim 20, in which the segmentation runs by means of vertical cracksthrough both ceramic layers (10 ^(III); 13 ^(IV)).
 23. The layer systemas claimed in claim 20, in which numerous vertical cracks extend up tothe attachment layer.
 24. The layer system as claimed in claim 22, inwhich a number of, more particularly numerous, vertical cracks extendfrom the surface up to the attachment layer.